A Turkish tank near Mount Barsaya, northeast of Afrin, Syria. (Khalil Ashawi/Reuters)
Opinion writer

Talking with Gen. Joseph Votel, the commander of American troops in the Middle East, is a paradoxical reminder of the limits of U.S. military power to determine political outcomes. American bombs helped destroy the Islamic State in Syria, but they can't stitch the rag doll of the Syrian nation back together.

Syria's plight actually got a bit worse this week, as Turkey invaded the border region known as Afrin. Turkey says it's protecting itself against the Syrian Kurdish organization known as the PKK, which dominates Afrin and which Turkey regards as a terrorist group. The problem is that related Syrian Kurdish forces (under a different name) have been the United States' most important ally in defeating the Islamic State.

The flashpoint is a town in northern Syria called Manbij, occupied by the Syrian Kurds and their U.S. military advisers. Turkish President Recep Tayyip Erdogan threatened last week to attack Manbij. A senior Trump administration official told me bluntly Tuesday: "Threats to our forces are not something we can accept." That's what the unraveling U.S. relationship with "NATO partner" Turkey has come to: military brinkmanship.

What's happening now in Syria is that history is resuming, after the bloody distraction of the Islamic State. Long-standing grievances that were postponed while a U.S.-led coalition defeated the caliphate have returned with a vengeance. Turkey, Iran, Israel, Jordan, Russia and the United States are all pursuing their self-interests. The space separating these forces has collapsed — putting U.S. troops perilously close to collision with Russia, Turkey and Iran.

The U.S. military three years ago was given the task of crushing the Islamic State. Votel and other commanders have largely accomplished that mission, using innovative partnerships and tactics. But they couldn't erase local hatreds or conjure up stable governance.

Votel was cautious in describing the United States' future mission in Syria when we talked last week at his headquarters here and during a visit to a training base. The presence of the roughly 1,500 U.S. troops remaining in Syria will be "conditions-based," he said. The troops will focus on "stabilization" rather than nation-building, seeking to "enhance security so people can get back to their homes," and supporting U.N. Security Council resolutions calling for an independent, united Syria.

U.S. officials speak as if America isn't taking sides in Syria, now that the Islamic State is shattered. And certainly, the United States should move now to embrace all the pieces of Syria's ethnic mosaic. But America shouldn't forget its friends, either, or these haunting casualty numbers: In the final decisive battle to take the Islamic State capital of Raqqa, the Kurdish-led Syrian Democratic Forces (SDF) suffered 650 deaths, Votel says. American deaths in Raqqa were zero.

The United States needs to bolster Sunni Arabs in Syria, lest the Islamic State return. But American commanders know that it's the Kurds (whom the Turks now say they want to destroy) who have done the bulk of the fighting and dying. The civilian death toll in the Islamic State conflict hasn't been well- ­calculated, but it was horrific.

Votel visited the ruined city of Raqqa on Monday. He told reporters that the campaign there was "ugly" but necessary. When we talked last week, he said that in the last phase of the Islamic State campaign, U.S. advisers and air power would partner with the SDF in a war of "annihilation" against "hundreds" of Islamic State fighters who are trapped in the lower Euphrates valley. U.S. commanders worry that their SDF allies will be pulled away from this essential mopping-up operation to fight the invading Turks.

A sign of the new post-Islamic State crackup in Syria was this headline in the Turkish newspaper Yeni Safak about Votel's arrival in the war zone: "U.S. commander visits . . . terrorists in Syria's Raqqa." That bodes ill.

Like other senior American officials, Votel stressed to me that the United States recognized Turkey's "legitimate concerns," and described it as a "good partner" that has done "a really good job of border security" over the past year. Soothing words aside, the Trump administration recognizes that the relationship with Turkey is dangerously near the breaking point.

As Erdogan climbs further out on the limb with his invasion, the United States' goal should be to broker dialogue between Turkey and the Kurds — not just in Syria but also in Turkey itself, with its large Kurdish minority population. Erdogan's greatest political and economic successes came in the years when he attempted reconciliation with the Kurds, including the PKK.

As the Islamic State campaign ends, old regional feuds resume. America can't stop Turkey, Russia and Iran from making mistakes. But this isn't the time to be pulling out America's 1,500 advisers from northeast Syria and creating an even bigger vacuum.

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